An exemplary Personal Communication Service (PCS) system 20 is shown in FIG. 1. PCS system 20 includes wireless terminals 22, base stations 24, switches 26, and a fixed network such as a public switched telephone network (PSTN) 28. Each base station 24 serves many wireless terminals 22 simultaneously. Each switch 26 connects many base stations 24 to PSTN 28. Wireless terminals 22 and base stations 24 include transmitters and receivers to exchange radio frequency (RF) communication signals.
Code division multiple access (CDMA) is a class of modulation that uses specialized codes to provide multiple communication channels in a designated segment of the electromagnetic spectrum. With CDMA, there are no restrictions on when transmission may take place or what frequency may be used in an allocated channel. In short, there are no restrictions on time or bandwidth. Each transmitter may transmit whenever it wishes and can use any or all of the bandwidth allocated a particular channel. Adding additional code sequences simply degrades voice quality.
CDMA is referred to as spread-spectrum multiple access. Transmissions can spread throughout the entire allocated bandwidth spectrum. Transmissions are separated through envelope encryption/decryption techniques. That is, the transmissions are encoded with a unique binary word called a chip code. Each transmitter has a unique chip code. To receive a particular transmission, a receiver must know the chip code for the particular transmitter.
CDMA communication systems differ from analog systems in that multiple users share one carrier frequency in a frequency band simultaneously. There are multiple frequency bands in the electromagnetic spectrum available for the use of mobile communications. A problem exists, however, that frequency bands are a scare commodity. Consequently, the demand for frequency bands is greater than the supply. As a result, service providers of mobile communications obtain frequency bands as they become available. Typically, the acquired frequency bands are segregated from each other by other bands. A given provider is often granted two or more non-contiguous or segregated frequency bands. Furthermore, different providers typically have their own frequency bands.
In the past, to operate in a pair of segregated frequency bands, two sets of equipment dedicated to each frequency band was required. For instance, separate antennas, cables, and radio/signal processing hardware were required for each frequency band. What is needed is a system and method that would allow operation in multiple segregated frequency bands by one set of hardware.